Pedogenic pathways and deep weathering controls on soil organic carbon in Pacific Northwest forest soils
Pedogenic pathways and deep weathering controls on soil organic carbon in Pacific Northwest forest soils
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DOI：
10.1016/j.geoderma.2023.116531
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发表时间：
2023-08
期刊：
影响因子：
6.1
通讯作者：
Brooke D. Hunter;J. Roering;P. Almond;O. Chadwick;M. Polizzotto;Lucas C. R. Silva
中科院分区：
文献类型：
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作者：
Brooke D. Hunter;J. Roering;P. Almond;O. Chadwick;M. Polizzotto;Lucas C. R. Silva
表征土壤中有机碳的分布和动态对于量化全球碳循环的变化至关重要。特别是，近地表和深层（>1米）土壤有机碳（SOC）动态的风化控制已被提出，但有限的数据使我们无法预测SOC的地形复杂的景观和量化的气候变化和扰动，如野火或土地管理，影响SOC的股票。为了促进我们的理解如何风化改变土壤地球化学和影响SOC存储，我们综合了以前的数据与新的分析Siuslaw河土壤年代序列从梯田在俄勒冈州海岸山脉，一个地区，拥有最丰富的SOC库存在美国大陆。我们分析了土壤地球化学，物理性质和SOC存储之间的关系如何随土壤的风化状态和路径而变化，这些土壤跨度为0.041至990 kyr，深度从1 m到>10 m。为了区分影响不同深度SOC储存的关键属性和过程，我们将分析分为三个深度区间：0-30，30-100和>100 cm。我们的研究结果表明，控制SOC股票的过程随时间和深度的变化系统，由于风化对土壤性质和成壤发展的影响。在30 kyr，我们观察到的SOC股票在顶部100厘米的峰值与草酸盐萃取的铝和铁浓度的峰值相一致，代表二次不良结晶矿物，这是与以前的研究一致。我们还观察到>30 kyr土壤的浅层SOC储量下降，因为结晶不良的矿物质被更稳定的结晶形式所取代，土壤变得以粘土为主。在120 kyr时，100 cm以下的SOC开始对总SOC概况清单有显著贡献，到990 kyr时，这一部分占总SOC存量的40%以上。两者合计，我们的研究结果表明，总SOC库存增加，随着土壤年龄的增加，基岩风化的强度加深的临界区，创造容纳空间深SOC存储。这些研究结果揭示了结晶性差的矿物和SOC之间的密切联系，并建议在关键区土壤发育的系统分析提供了一个一阶约束SOC股票。
Characterizing the distribution and dynamics of organic carbon in soil is critical for quantifying changes in the global carbon cycle. In particular, weathering controls on near-surface and deep (>1 m) soil organic carbon (SOC) dynamics have been proposed but limited data prevents us from predicting SOC over topographically complex landscapes and quantifying how changes in climate and perturbations, such as wildfire or land management, influence SOC stocks. To advance our understanding of how weathering alters soil geochemistry and influences SOC storage, we synthesize previous data with a new analysis of the Siuslaw River soil chronosequence from terraces in the Oregon Coast Range, a region that harbors the richest SOC inventories in the continental US. We analyze how the relationships between soil geochemistry, physical properties, and SOC storage vary with weathering status and pathways across soils that span 0.041 to 990 kyr and vary in depth from 1 m to >10 m. To distinguish the key properties and processes influencing SOC storage at different depths, we break our analysis into three depth intervals: 0–30, 30–100, and >100 cm. Our results suggest that the processes that control SOC stocks vary systematically with time and depth owing to weathering impacts on soil properties and pedogenic development. At 30 kyr we observe a peak in SOC stock in the top 100 cm coincident with a peak in oxalate extractable Al and Fe concentrations, representing secondary poorly crystalline minerals, which is consistent with previous studies. We also observe a decline in shallow SOC stock for >30 kyr soils as poorly crystalline minerals are replaced by more stable crystalline forms and soils become clay dominated. At 120 kyr, SOC below 100 cm starts to contribute significantly to the total SOC profile inventory and by 990 kyr, this fraction composes >40% of the total SOC stock. Taken together, our results indicate that total SOC stock increases with soil age as the increased intensity of bedrock weathering deepens the critical zone, creating accommodation space for deep SOC storage. These findings reveal the intimate link between poorly crystalline minerals and SOC and suggest that systematic analysis of soil development in the critical zone provides a first-order constraint on SOC stocks.